Podrobnosti záznamu

Název
    Interpretation of bidimensional fluid inclusion microthermometric data in terms of pressure and compositional variations in gold-bearing fluids: an example from the Libčice and Kasejovice deposits, Czech Republic
Údaj o odpovědnosti
    Jiří Zachariáš
Další názvy
    Interpretace dvourozměrných mikrotermometrických měření fluidních inkluzí vzhledem k variacím ve složení a tlaku zlatonosných fluid: příklady z ložisek Libčice a Kasejovice, Česká republika
Autor
    Zachariáš, Jiří
Jazyk
    anglicky
Zdrojový dokument - seriál
    Journal of the Czech Geological Society
Svazek/č.
    Vol. 47, no. 3-4
Strany
    p. 123-132
Rok
    2002
Poznámky
    10 obr., 24 bibl.
    České resumé
    il.
    Zkr. název ser.: J. Czech geol. Soc.
Předmětová skupina
    Barrandien
    inkluze fluidní
    katodoluminiscence
    kontrola geochemická
    kontrola litologická
    křemen
    ložisko hydrotermální
    rudy Au
    středočeský pluton
Geografické jméno
    ČR-Čechy
    Kasejovice (Plzeň-jih)
    Libčice (Příbram)
Klíčové slovo
    Bidimensional
    Compositional
    Czech
    Data
    Deposits
    Example
    Fluid
    Fluids
    Gold-bearing
    Inclusion
    Interpretation
    Kasejovice
    Libčice
    Microthermometric
    Pressure
    Republic
    Terms
    Variations
Abstrakt (anglicky)
   Systematic mapping of selected fluid inclusion microthermometric characteristics is combined with standard microscopy and various cathodoluminescence techniques to provide detailed information on the evolution of pressure, temperature and compositional variations in hydrothermal fluids. The advantage of such a complex approach is demonstrated on samples from Variscan mesothermal gold deposits of Libčice and Kasejovice in Central Bohemia. Primary fluid inclusions from remnants of original quartz grains were studied at the Libčice deposit. They display systematic zoning of C0,-melting and homogenization temperatures [Tm-CO2: -57.5 to -65.0 °C and Th-CO2: +24 to -21°C (always to liquid)], and little variation in the other parameters [salinity: 1-5 wt. per cent NaCl eq., total homogenization: +340 to +370 °C (to liquid, or critical), degree of fill: -0.5]. These variations reflect an increase in the amount of CH4 in the gaseous phase of fluid inclusions from 1 to 50 mol.
   per cent from the cores towards the rims of quartz grains. In addition, variations in fluid density (0.70-0.88 g/cm3) were observed. The data are discussed in terms of P-T-X variations: the difference in fluid pressure between the grain core and grain rim during quartz gangue precipitation is estimated to equal nearly 2000 bars. The gradual evolution of CH4/CO2 ratio is interpreted as being due to mixing between initial CO2-rich fluids of deep provenance with local CH4-enriched fluids. The former were probably produced by large-scale regional devolatilization, while the latter are a result of local "in situ" devolatilization of organic carbon-rich Lečice Member black shales in a narrow contact-metamorphic zone of the CBPC. An example of a trail of secondary aqueous fluid inclusions from the Kasejovice deposit exhibits systematic variations in the total homogenization temperatures (+180 to +130 °C, to liquid).
   These are interpreted as pressure and temperature variations during sealing of microfractures
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
    U
Datum vložení
    21. 3. 2008
Datum importu
    8. 8. 2012